Layers of Security

Theft-deterrent systems fall into two general categories: active and passive. Active devices, as the name implies, require owners to take some action, such as setting the alarm, installing a locking device, etc. Passive systems require no action; they engage automatically once the keys are removed or the doors are locked. Engine immobilizers are a popular passive device.

Experts agree that theft-deterrent devices don't guarantee your car's security but they decrease the chances for theft. Thieves spotting such devices likely will move on to easier-to-steal vehicles that aren't protected.

To that end, experts recommend what they call "layered protection." The rationale is that the more layers of protection on your car, the harder it will be to steal.

The first layer of protection is simple common sense: Remove your keys from the ignition; lock your doors and close your windows; and park in safe, well-lit areas.

The second layer of protection is a visible or audible device, which alerts thieves that your vehicle is protected. Besides audible alarms and visible protection devices, others include:

The vehicle identification number etched or written on all of the car windows and major parts of the vehicle that thieves know make it easier for the stolen car to be traced. This can be an inexpensive, do-it-yourself project because the number can be painted or written with an indelible marker under the engine hood, on the trunk lid or on the battery.

A brake-and-steering-wheel lock system that secures the steering wheel to the brake pedal and immobilizes the controls.

A steering-wheel lock that consists of a steel rod that attaches to the wheel and hinders steering. Many can be bought for less than $100.

An ignition and steering-column collar, which is made up of a lockable steel shield that encases the steering column to prevent access to the ignition. Most column covers are custom-made by aftermarket suppliers and usually apply to a certain make or model. Prices start around $30.

Immobilizing devices make up the third layer of protection. Tools such as starter disablers, fuse cutoffs and kill switches prevent thieves from bypassing the ignition and hot-wiring the vehicle. Other systems feature smart keys, which carry computer chips or coded radio frequencies. The engine can't be started without the exact key. Vehicles with engine immobilizers generally are stolen by hauling them away on flatbed trucks, a visible act that takes more time.

Tracking devices are the top layer of protection. These devices are systems that help recover stolen vehicles. Systems such as General Motors' OnStar communication service and LoJack allow police to track the vehicle if it is stolen.

LoJack installs a transmitter the size of a chalkboard eraser on a car. The location is kept secret so thieves can't easily disarm it. The transmitter starts working only when police, who receive a stolen-car report, activate it by remote control. Check with your dealer if you want to place one on your new car, or with an authorized seller for a car you already own or a used car.

If you choose to install a tracking system, be sure to apply warning decals to your vehicle. Making thieves aware of these tracking devices may make them think twice before trying to steal your car.

What you drive should help determine the kind of protection you need. Heavier layers of protection should be considered if you drive a car that's a favorite among thieves.